In general, an X-ray imaging device includes an X-ray image sensor. An X-ray generator applies X-rays to an object such as a human body from multiple directions, and the X-ray image sensor measures an intensity distribution of the X-rays that transmitted through the object (that is, a projection of the object).
There has been disclosed an example of such an X-ray image sensor including, for example, a thin film transistor (hereinafter may be referred to as “TFT”) formed on a transparent substrate, a first protective insulating film covering the TFT and other components together, a capacitor electrode formed on the first protective insulating film, at least a portion thereof shielding the TFT, a second protective insulating film formed on the first protective insulating film to cover the capacitor electrode, and a pixel electrode formed on the second protective insulating film to be connected to one of terminals of the TFT. This X-ray image sensor is configured such that a storage capacitor formed by the capacitor electrode, the second protective insulating film and the pixel electrode accumulates charges generated by applying X-rays to a conversion film (see, for example, Patent Document 1).